Navigation apparatus

ABSTRACT

A navigation apparatus includes a map data acquiring means  11   a   , 11, 12 , and  5  for acquiring map data including data about roads for which whether or not a car pool lane is also provided is specified; a current position determining means  13, 14, 15 , and  10  for determining a current position; and a route searching unit  130  for searching for a route from the current position determined by the current position determining means to a destination inputted by an input unit on the basis of the map data acquired by the map data acquiring means, and for, when a road where a car pool lane is also provided is included in a route acquired through the route search, presenting, as a recommended route, the route using the car pool lane if the distance over which the road will be traveled is equal to or longer than a predetermined value.

CROSS REFERENCE TO RELATED APPLICATIONS:

This nonprovisional application is the National Phase of PCT ApplicationNo. PCT/JP2007/069605 filed on Oct. 5, 2007 which claims benefit under35 U.S.C. §119 of Japanese Patent Application No. JP2006-327409 filed onDec. 4, 2006. The entire contents of the above application is herebyincorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a navigation apparatus which performs asearch for a route including a car pool lane. More particularly, itrelates to a technology of determining a recommended route according toa distance over which a vehicle will use a highway where a car pool laneis also provided.

BACKGROUND OF THE INVENTION

A conventional navigation apparatus displays the current position of avehicle which is determined by a vehicle position determining unit on adigital map (simply referred to as a “map” from here on) displayed on adisplay unit while superimposing the current position on the map.Furthermore, the conventional navigation apparatus searches for arecommended route from the current position of the vehicle which isdetermined by the vehicle position determining unit to a destinationinputted via an input unit, and displays the recommended route on themap. The conventional navigation apparatus then carries out a routeguidance of the recommended route on the basis of the shapes of roadlinks read from a recording medium.

By the way, recent years have seen increase in the number of cars ownedby individuals and occurrence of traffic congestions in various placesof roads. Especially, most of vehicles travelling along a highway orexpressway (simply referred to as a “highway” from here on in thisspecification) which is extending toward a big city and which is usedfor commuting or the like are occupied by only one person and thisresults in increase in traffic congestions. In order to solve thisproblem, there have been constructed highways where traffic isrestricted by law according to the conditions of vehicles including thenumber of passengers and vehicle types.

For example, a car pool lane (Car Pool Lane) which is adopted by a roadsystem mainly seen in big cities of North American is an example. A carpool lane is also called an HOV lane (High Occupancy Vehicle Lane), andis a lane along which, for example, only vehicles in each of which twoor more persons are riding are granted to travel. For example, a lanewhich is also provided on a highway is known as a car pool lane. A roadsystem which adopts such a car pool lane provides users with apreferential treatment that makes it possible to arrive at thedestination in a shorter time when they travel along a car pool lane soas to prod users to share a vehicle with one or more persons, therebyreducing the traffic as a whole and therefore reducing trafficcongestions.

As a technology relevant to such a car pool lane, patent reference 1discloses a vehicle-mounted navigation apparatus which searches for arecommended route in consideration of the number of passengers. Thisvehicle-mounted navigation apparatus has a storage unit for storing mapdata including link data about each link which constructs a road on amap. As for a car pool link on which restrictions of prohibiting avehicle which is not occupied by two or more persons from traveling areimposed, the vehicle-mounted navigation apparatus uses link dataincluding information showing that such restrictions are imposed on thecar pool link to search for a recommended route from the place ofdeparture to the destination. Furthermore, when a car pool link isincluded in the constitution links which construct the recommendedroute, the vehicle-mounted navigation apparatus receives an input of thenumber of passengers, and searches for a recommended route from theplace of departure to the destination by using the link data to excludelinks along which the vehicle cannot travel because the received numberof passengers does not meet a certain criterion.

Patent reference 2 discloses a route searching apparatus which canperform a search for a route in consideration of the conditions of avehicle through an easy operation. This route searching apparatus isprovided with a map data acquiring unit for acquiring map data definedby nodes and road links, a route searching unit for searching for aroute to a destination before the conditions of the vehicle are set up,taking into consideration a road link corresponding to a particular roadfor which whether or not the vehicle can travel according to theconditions of the vehicle is determined, the road link being included inthe map data acquired by the map data acquiring unit, and an output unitfor outputting the route searched for by the route searching unit.

-   [Patent reference 1] JP, 2005-061988,A-   [Patent reference 2] JP, 2005-083758,A

In many cases, a car pool lane currently provided is disposed as acentral one of a plurality of lanes of a highway. A problem is thereforethat when a vehicle enters a highway from a local street via an entranceof the highway or a connection road to the highway and then enters a carpool lane from an general purpose lane of the highway, the vehicle hasto cross a plurality of driving lanes of the highway along which manyvehicles are travelling at a high speed until entering the car poollane, and this entails danger to the driver of the vehicle and forcesthe driver to do a burdensome driving operation. Furthermore, becausethe number of vehicles which are travelling along a highway at a highspeed changes greatly depending on what day of the week it is or whattime zone it is, and low-acceleration vehicles and large-sized vehiclesalso travel along a highway, it is dangerous to cross a plurality ofdriving lanes. This problem similarly arises in a case in which avehicle goes out of a car pool lane to a highway via an exit of the carpool lane, crosses a general purpose lane of the highway, and then goesout of the highway to a local street via an exit or a connection road ofthe highway.

However, no measures against the above-mentioned problem are taken inthe route search of conventional navigation apparatuses, andconventional navigation apparatuses simply perform a search for a routeincluding a car pool lane as a part thereof. Therefore, even if asection in which the vehicle uses a car pool lane is short, arecommended route including the car pool lane is presented to the user.When the user is going to drive the vehicle along the presentedrecommended route, in order to enter a car pool lane from a local streetvia general purpose lanes of a highway, and then go out of the car poollane to a local street via general purpose lanes of the highway, thevehicle has to drive the vehicle to cross a plurality of driving lanesof the highway two times during travel over a short distance. Therefore,the above-mentioned problem of entailing danger to the user and alsoforcing the user to do a burdensome driving operation is left behind.

The present invention is made in order to solve the above-mentionedproblem, and it is therefore an object of the present invention toprovide a navigation apparatus which can provide a recommended routewhich enables the user to use a car pool lane properly and travel alongthe car pool lane safely for the user.

DISCLOSURE OF THE INVENTION

In order to solve the above-mentioned problem, a navigation apparatus inaccordance with the present invention includes: a map data acquiringmeans for acquiring map data including data about roads for whichwhether or not a car pool lane is also provided is specified; a currentposition determining means for determining a current position; an inputunit for inputting a destination; and a route searching unit forsearching for a route from the current position determined by thecurrent position determining means to the destination inputted by theinput unit on a basis of the map data acquired by the map data acquiringmeans, and for, when a road where a car pool lane is also provided isincluded in the route which the route searching unit has acquiredthrough the search, presenting, as a recommended route, the route usingthe carpool lane when a distance over which the road will be traveled isequal to or longer than a predetermined value.

Because the navigation apparatus in accordance with the presentinvention is constructed in such a way as to, when a road where a carpool lane is also provided is included in the route acquired through thesearch, present, as a recommended route, the route using this car poollane if the distance over which this road will be traveled is equal toor longer than a predetermined value, the navigation apparatus does notpresent the car pool lane as the recommended route when the distanceover which the road will be traveled is shorter than the predeterminedvalue. Therefore, when driving the vehicle to travel along therecommended route, the user does not need to cross general purpose lanesof a highway and to make a useless lane change, and can therefore drivesafely while using car pool lanes properly.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a block diagram showing the structure of a navigationapparatus in accordance with Embodiment 1 of the present invention;

FIG. 2 is a flow chart showing the operation of the navigation apparatusin accordance with Embodiment 1 of the present invention;

FIG. 3 is a view showing an example of a destination setup screen whichis displayed in the navigation apparatus in accordance with Embodiment 1of the present invention;

FIG. 4 is a view showing an example of a search condition setup screenwhich is displayed in the navigation apparatus in accordance withEmbodiment 1 of the present invention;

FIG. 5 is a view showing an example of a car pool lane setup screenwhich is displayed in the navigation apparatus in accordance withEmbodiment 1 of the present invention; and

FIG. 6 is a view for explaining a route search using a car pool lane inthe navigation apparatus in accordance with Embodiment 1 of the presentinvention.

PREFERRED EMBODIMENTS OF THE INVENTION

Hereafter, in order to explain this invention in greater detail, thepreferred embodiments of the present invention will be described withreference to the accompanying drawings. Embodiment 1.

FIG. 1 is a block diagram showing the structure of a navigationapparatus in accordance with Embodiment 1 of the present invention. Thisnavigation apparatus is comprised of a navigation unit 1, a monitor 2, aremote controller (abbreviated as a “remote control” from here on) 3, anaudio speaker 4, and an external memory 5.

The navigation unit 1 forms the heart of the navigation apparatus, andcarries out processes, such as a map display, a route search, a routedisplay, and a route guidance.

Especially, a process of performing a search for a route while judgingwhether to use a car pool lane as a recommended route, which is afeature of the present invention, is also performed by this navigationunit 1. The details of this navigation unit 1 will be mentioned below.

The monitor 2 is comprised of, for example, an LCD (Liquid CrystalDisplay) , and displays a map, a vehicle position mark, a recommendedroute to a destination, and various other messages according to displaydata sent thereto from the navigation unit 1. A remote control lightreceiving unit 21 is disposed in this monitor 2. The remote controllight receiving unit 21 receives a light signal sent thereto from theremote control 3, and sends the light signal, as an input signal, to thenavigation unit 1 via the monitor 2.

The remote control 3 corresponds to an input unit, a usable or unusablesetting means, and a distance setting means of the present invention,and is used by the user to scroll a map displayed on the monitor 2, toinput a destination, to set up either a required distance from anentrance of a highway where a car pool lane is also provided to anentrance of the car pool lane or a required distance from an exit of acar pool lane to an exit of a highway where the car pool lane is alsoprovided, to set up whether to use a car pool lane as a route accordingto a traveled distance, to set up a traveled distance over which thevehicle will travel a highway where a car pool lane is also provided,and to answer a message for urging the user to do a certain operationwhich is outputted from the monitor 2 or the audio speaker 4. Instead ofthe remote control 3 or together with the remote control 3, a touchpanel can be disposed for enabling the user to directly touch a touchsensor mounted on the screen of the monitor 2 to input various pieces ofinformation.

The audio speaker 4 outputs, by voice, a route guidance messageincluding a guidance about car pool lanes according to audio data sentthereto from the navigation unit 1. The external memory 5 is optional,and is comprised of, for example, an HDD (Hard Disk Drive). Map datasimilar to map data stored in a recording medium 11 a inserted into adisk drive unit 11 which will be mentioned below are stored in thisexternal memory 5. Use of this external memory 5 makes it possible toaccess the map data at a high speed, as well as to store a lot of mapdata.

Next, the details of the navigation unit 1 will be explained. Thenavigation unit 1 is comprised of a control unit 10, the disk drive unit11, a map data storage unit 12, a GPS (Global Positioning System)receiver 13, a speed sensor 14, a gyro sensor 15, a road informationreceiver 16, a human-machine interface (abbreviated as an “HMI” fromhere on) unit 100, a map display unit 110, a map matching unit 120, aroute searching unit 130, and a route guidance unit 140.

The control unit 10 is comprised of, for example, a microcomputer, andcontrols the whole of this navigation unit 1. The HMI unit 100, the mapdisplay unit 110, the map matching unit 120, the route searching unit130, and the route guidance unit 140 are comprised of an applicationprogram which operates under the control of this microcomputer.

When the recording medium 11 a, such as a DVD (Digital Versatile Disc)or a CD (Compact Disc) , in which a map database including map data isstored is inserted thereinto, the disk drive unit 11 plays back acontent recorded in the recording medium. The map data are defined bynodes, road links, etc., and include link information, such asintersection construction links, destination area data, car pool lanedata, and road number data. Whether or not a car pool lane is alsoprovided is specified in a road link.

Carpool lane data include lane information (the position of a car poollane in all lanes), information about the types of vehicles which canuse the car pool lane (e.g., a general vehicle, a bus, a track, anemergency vehicle, a hybrid vehicle, a motorcycle, and so on),information about the number of passengers which is required of the userto use the car pool lane, information about dates or days of the week onwhich vehicles can use the car pool lane, and a time zone in whichvehicles can use the car pool lane, information about the toll fee ofusing the car pool lane, etc. The map data played back by this diskdrive unit 11 are sent to the map data storage unit 12.

The map data storage unit 12 temporarily stores the map data sentthereto from the disk drive unit 11 or the external memory 5. A map dataacquiring means in accordance with the present invention is comprised ofeither the disk drive unit 11 to which the recording medium 11 a ismounted or the external memory 5, and the map data storage unit 12. Themap data stored in this map data storage unit 12 are used for display ofinformation about a car pool lane, a map, roads, various icons, otherinformation, etc., a route search, a route guidance, etc.

The GPS receiver 13 detects the current position of the vehicle on thebasis of GPS signals from GPS satellites which are received via anantenna. Current position data showing the current position of thevehicle detected by this GPS receiver 13 are sent to the control unit10. The speed sensor 14 detects the traveling speed of the vehicle onthe basis of an external signal sent thereto from the vehicle in whichthis navigation apparatus is mounted. Speed data showing the travelingspeed of the vehicle detected by this speed sensor 14 are sent to thecontrol unit 10.

The gyro sensor 15 detects the traveling direction of the vehicle.Direction data showing the traveling direction of the vehicle detectedby this gyro sensor 15 are sent to the control unit 10. The control unit10 detects the current position of the vehicle with self-containednavigation on the basis of the speed data sent thereto from the speedsensor 14 and the direction data sent thereto from the gyro sensor 15.Because the navigation apparatus can detect the current position of thevehicle with self-contained navigation even if the navigation apparatuscannot detect the current position of the vehicle using the GPS receiver13 when, for example, the vehicle is running through a tunnel, thenavigation apparatus can always detect the current position of thevehicle correctly. A current position determining means in accordancewith the present invention is comprised of the GPS receiver 13, thespeed sensor 14, the gyro sensor 15, and the control unit 10 whichprocesses data sent thereto from these components.

The road information receiver 16 receives a road information signaltransmitted from, for example, an external road traffic datacommunications system. The road information signal received by this roadinformation receiver 16 is sent to the control unit 10. The control unit10 generates a message showing congestion information about congestionon roads on the basis of the road information signal received from theroad information receiver 16, and notifies the message to the user viathe monitor 2 and the audio speaker 4.

Under the control of the control unit 10, the HMI unit 100 processeseither a command which is generated when the user manipulates anot-shown control panel or a command sent thereto, as an input signal,from the remote control 3 via the monitor 2 including the remote controllight receiving unit 21. This HMI unit 100 carries out communicationsbetween the navigation apparatus and the user.

The map display unit 110 generates drawing data for making the monitor 2display a map, an intersection guidance figure, information about a carpool lane, a telop for notifying various pieces of information to theuser, etc. under the control of the control unit 10. The drawing datagenerated by this map display unit 110 are sent to the monitor 2 asdisplay data, so that a map, a vehicle position mark, a recommendedroute to the destination, a intersection guidance figure, informationabout a car pool lane, etc. are displayed on the screen of the monitor2.

Under the control of the control unit 10, the map matching unit 120associates the vehicle position which is generated on the basis ofeither the current position data from the GPS receiver 13 or the currentposition data detected with autonomous navigation with the map shown bythe map data read from the map data storage unit 12 so as to form avehicle position mark on the map.

Under the control of the control unit 10, the route searching unit 130searches for a recommended route from the current position of thevehicle to the destination which the user has set up by using the remotecontrol 3 according to search conditions and car pool lane useconditions which the user has set up by using the remote control 3. Thisroute searching unit 130 can perform both a search for a route whichenables use of car pool lanes and a search for a route which disablesuse of car pool lanes.

When performing a search for a route which enables use of car poollanes, if a highway where a car pool lane is also provided is includedin the route acquired through the route search and the distance from anentrance of the highway to an entrance of the car pool lane is equal toor longer than a predetermined value A and the distance from an exit ofthe car pool lane to an exit of the highway is equal to or longer than apredetermined value B, this route searching unit 130 presents the routewhich uses the car pool lane as a recommended route to the user.

Furthermore, when performing a search for a route which enables use ofcar pool lanes, if a highway where a car pool lane is also provided isincluded in the route acquired through the route search and the distanceover which the vehicle will travel the highway is equal to or largerthan a predetermined value, this route searching unit 130 presents theroute which uses the car pool lane which is also provided on the highwayas a recommended route, whereas if a highway where a car pool lane isalso provided is included in the route acquired through the routesearch, but the distance over which the vehicle will travel the highwayis smaller than the predetermined value, the route searching unitpresents another route which does not use the car pool lane which isalso provided on the highway as a recommended route.

Irrespective of whether the vehicle will travel along the recommendedroute acquired through the route search performed by the route searchingunit 130, the route guidance unit 140 generates a route guidance figureand a voice guidance message including the information about a car poollane as the vehicle travels. The route guidance figure is displayed onthe monitor 2, and the voice guidance message is outputted from theaudio speaker 4.

Next, the operation of the navigation apparatus which is constructed asmentioned above will be explained focusing on the route searchingprocess of performing a search for a route including a car pool lanewith reference to a flow chart shown in FIG. 2, screen display examplesshown in FIGS. 3 to 5, and an explanatory drawing of the operation shownin FIG. 6.

When the power supply of the navigation apparatus is switched on, thenavigation apparatus acquires the current position data and map datafirst (step ST11). More specifically, the control unit 10 sends eitherthe current position data acquired from the GPS receiver 13 or thecurrent position data detected with autonomous navigation to the mapmatching unit 120. Furthermore, the disk drive unit 11 reads map datafrom the recording medium 11 a set thereto, and stores them in the mapdata storage unit 12. The map matching unit 120 carries out a matchingprocess of reading the map data from the map data storage unit 12, andsuperimposing the vehicle position mark on the map at a positioncorresponding to the current position data received from the controlunit 10. The map data on which this matching process has been performedare sent to the map display unit 110. The map display unit 110 generatesdrawing data on the basis of the map data sent thereto from the mapmatching unit 120, and sends the drawing data to the monitor 2 asdisplay data.

A display of a current position screen is then produced (step ST12).More specifically, the monitor 2 draws a map whose center corresponds tothe current position of the vehicle on the basis of the display datareceived from the map display unit 110. Thereby, the map whose centercorresponds to the current position of the vehicle shown by the vehicleposition mark is displayed, as the current position screen, on themonitor 2.

A setup of a destination is then performed (step ST13). Morespecifically, when the user performs an operation of instructing thenavigation apparatus to set up a destination, the navigation apparatusdisplays a destination setup screen as shown in FIG. 3 on the monitor 2.In this destination setup screen, portions each enclosed by a rectangleare buttons, and the user is enabled to select a desired button by usingthe remote control 3 to make the navigation apparatus carry out afunction allocated to the button. The same goes for each screen whichwill be explained hereafter. The user uses the remote control 3 to setup a destination (and a via-place as needed) on the map displayed on themonitor 2 by using an address search, a facility name search, a phonenumber search, or the like. The monitor 2 sends data showing thedestination set up by the user with the remote control 3 to the routesearching unit 130 of the navigation unit 1.

A setup of search conditions is then performed (step ST14). Morespecifically, when a setup of a destination in step ST13 is completed,the navigation apparatus displays a search condition setup screen asshown in FIG. 4 on the monitor 2. The user then sets up conditions forthe route search which are displayed on the monitor 2 by using theremote control 3. Concretely, the user sets up a higher-priority searchcondition by pushing one of a button showing “fastest root”, a buttonshowing “shortest route”, and a button showing “easy root”, the buttonsshowing higher-priority route conditions, respectively. The user alsosets up whether the navigation apparatus can use each of the followingitems: a highway, a toll road, a ferry, an avoidance route area, and atime-limited road by pushing a “use” button or a “nonuse” button.

A “map” button in the search condition setup screen shown in FIG. 4 isused in order to return the screen of the monitor 2 to the currentposition screen, an “enter” button is used in order to make the settingspermanent, an “initial setting” button is used in order to return thesearch conditions to initial ones, and a “return” button is used inorder to return the screen of the monitor to the previous screen. Whenthe “enter” button on this search condition setup screen is pushed, themonitor 2 shifts to settings about car pool lane use conditions whilesending data showing the set-up search conditions to the route searchingunit 130 of the navigation unit 1.

For the settings about car pool lane use conditions, a carpool lane(HOV) setup screen as shown in FIG. 5 is displayed. The user sets upcarpool lane use conditions by using this car pool lane setup screen.More specifically, the user sets up the following items: a distancerestriction, a distance, the number of lanes, a vehicle type, a settingof days of week, and a time zone setting for each of an “entrance” andan “exit” of a car pool plane as needed. When each of theabove-mentioned items is not changed, initial settings are adopted asthe car pool lane use conditions.

Concretely, in a case of making a setting for the item of “distancerestriction”, when imposing a distance restriction, the user pushes a“Yes” button, whereas when not imposing any distance restriction, theuser pushes a “No” button. Furthermore, when making settings for theitem of “distance”, the user sets up both a distance A km from anentrance of the highway where the carpool lane is also provided to anentrance of the car pool lane, and a distance B km from an exit of thecar pool lane to an exit of the highway where the car pool lane is alsoprovided. The user can change each of the distances by pushing either abutton disposed on a left side of the display of each of the distancesand having a leftward triangular mark attached thereto, or a buttondisposed on a right side of the display of each of the distances andhaving a rightward triangular mark attached thereto. The same goes foreach of the other items.

Furthermore, when making a setting for the item of “ number of lanes”,the user sets up the number of lanes extending from the entrance of thehighway which the user uses to the entrance of the car pool lane, orfrom the exit of the car pool lane to the exit of the highway. Inaddition, when making a setting for the item of “vehicle type”, the usersets up a vehicle type which the user uses (a general vehicle, a bus, atrack, an emergency vehicle, a hybrid vehicle, a motorcycle, or thelike) . Furthermore, when making a setting for the item of “setting ofdays of the week”, the user sets up days of the week on which the useruses the car pool lane. In addition, when making settings for the itemof “time zone setting”, the user sets up a time zone in which the useruses the car pool lane.

Furthermore, in a case of making a setting for an item of “HOV usehighway distance setting”, when using a car pool plane according to thetravelled distance over which the highway will be travelled, the userpushes a “Ye's” button, whereas when not using any car pool planeaccording to the travelled distance, the user pushes a “No” button. Inthis case, when the “Yes” button is pushed, the navigation apparatussets up (or changes) the distance (i.e., the distance over which thevehicle will travel the road where the car pool lane is also provided)as needed.

A “map” button in the car pool'lane setup screen shown in FIG. 5 is usedin order to return the screen of the monitor to the current positionscreen, an “enter” button is used in order to make the settingspermanent, an “initial setting” button is used in order to return thecar pool lane use conditions to initial ones, and a “return” button isused in order to return the screen of the monitor to the previousscreen. When the “enter button” on this search condition setup screen ispushed, the monitor 2 sends data showing the set-up car pool lane useconditions to the route searching unit 130 of the navigation unit 1.After that, the navigation apparatus advances the sequence to step ST15.

In step ST15, the navigation apparatus carries out a route search bymaking car pool lanes (HOV) be usable. More specifically, the routesearching unit 130 searches for a route from the current positiondetermined by the current position data received from the GPS receiver13 via the control unit 10 to the destination set up in step ST13according to the search conditions and the car pool lane use conditionswhich are set up in step ST14.

In this route search, when a highway where a car pool lane is alsoprovided exists in a route from the current position to the destination,the route searching unit judges whether to adopt the car pool lane as arecommended route as follows. More specifically, in a case in whichthere exist routes along each of which the vehicle enters a generalpurpose lane of a highway from a local street via an entrance of thehighway, and then enters a car pool lane, via an entrance of the carpool lane, from the general purpose lane of the highway, the routesearching unit does not adopt, as the recommended route, a route alongwhich the vehicle enters the car pool lane from an entrance of the carpool lane which is located at a distance shorter than a predetermineddistance A km from the entrance of the highway, but adopts a route alongwhich the vehicle enters the car pool lane from an entrance of the carpool lane which is located at a distance equal to or longer than thepredetermined distance A km from the entrance of the highway. As aresult, because the user does not need to drive the vehicle to cross aplurality of driving lanes during travel over a short distance, the usercan drive the vehicle to enter the car pool lane safely.

Furthermore, in a case in which there exist routes along each of whichthe vehicle enters an general purpose lane of a highway from a car poollane via an exit of the car pool lane, and then goes out of the generalpurpose lane of the highway to a local street via an exit of thehighway, the route searching unit does not adopt, as the recommendedroute, a route along which the vehicle enters the general purpose laneof the highway from an exit of the car pool lane located at a distanceshorter than a predetermined distance B km to the exit of the highway,but adopts, as the recommended route, a route along which the vehicleenters the general purpose lane of the highway from an exit of the carpool lane located at a distance equal to or longer than thepredetermined distance B km to the exit of the highway. As a result,because the user does not need to drive the vehicle to cross a pluralityof driving lanes during travel over a short distance, the user can drivethe vehicle to go out of the car pool lane safely. The above-mentionedpredetermined distance A km from an entrance of a highway and theabove-mentioned predetermined distance B km to an exit of a highway canbe changed according to at least one of the number of lanes of thehighway, the vehicle type, the days of the week, and the time zone whichare set up as the car pool lane use conditions.

Furthermore, when, in the route search in step ST15, “Yes” is selectedin the item of the HOV use highway distance setting on the car pool lanecondition setup screen (refer to FIG. 5) , the route searching unit 130adopts, as the recommended route, the car pool lane if the distance fromthe entrance of the highway which exists in the route acquired throughthe route search to the exit of the highway is longer than C km, asshown in FIG. 6( a), whereas the route searching unit does not adopt, asthe recommended route, the car pool lane if the distance from theentrance of the highway which exists in the route acquired through theroute search to the exit of the highway is equal to or shorter than Ckm, as shown in FIG. 6( b). As a result, when driving the vehicle totravel along the recommended route, the user does not need to crossgeneral purpose lanes of a highway and to make a useless lane change,and can therefore drive safely while using the car pool lane properly.In contrast, when “No” is selected in the item of the HOV use highwaydistance setting on the car pool lane condition setup screen, the routesearching unit neglects the distance C km from the entrance of thehighway which exists in the route acquired through the route search tothe exit, and does not use the distance for the judgment of whether touse the car pool lane as the recommended route.

When completing the route search in above-mentioned step ST15, thenavigation apparatus checks to see whether a car pool lane (HOV) isincluded in the route acquired through this route search (step ST16).When, in this step ST16, judging that no car pool lane (HOV) is includedin the route, the navigation apparatus sends data showing the routeacquired through the route search in step ST15 to the map display unit110 as data showing the recommended route. As a result, the map displayunit displays the recommended route acquired through the route search onthe monitor 2. After that, the navigation apparatus advances thesequence to step ST22 and starts a route guidance.

When, in above-mentioned step ST16, judging that a car pool lane (HOV)is included in the route, the navigation apparatus then shows a telopfor making the user select whether or not the user can use the car poollane (HOV) (step ST17). The navigation apparatus then checks to seewhether the user has made a selection of using the car pool lane (HOV)(step ST18). When, in this step ST18, judging that the user has made aselection of using the car pool lane (HOV), the navigation apparatussends the data showing the route acquired through the route search instep ST15 to the map display unit 110 as the data showing therecommended route. As a result, the map display unit displays therecommended route acquired through the route search on the monitor 2.After that, the navigation apparatus advances the sequence to step ST22and starts a route guidance.

When, in above-mentioned step ST18, judging that the user has made aselection of not using the car pool lane (HOV) , the navigationapparatus then carries out a route search again by making car pool lanes(HOV) be unusable (step ST19) , and further checks to see whether a carpool lane (HOV) is included in the route acquired through the routere-search in step ST19 (step ST20). The reason why the navigationapparatus checks to see whether a carpool lane (HOV) is included in theroute acquired through the route re-search is that the navigation has tosupport a case in which the destination is set up as a point on a carpool lane and a case in which the current position is on a car poollane.

When, in this step ST20, judging that no car pool lane (HOV) is includedin the route acquired through the route re-search, the navigationapparatus sends data showing the route acquired through the routere-search in step ST19 to the map display unit 110 as the data showingthe recommended route. As a result, the map display unit displays therecommended route acquired through the route re-search on the monitor 2.After that, the navigation apparatus advances the sequence to step ST22and starts a route guidance.

In contrast, when, in step ST20, judging that a car pool lane (HOV) isincluded in the route acquired through the route re-search, thenavigation apparatus then shows a telop for warning the user that anycar pool lane (HOV) avoidance route cannot be searched for (step ST21).In this case, the navigation apparatus sends the data showing the routeacquired through the route re-search in step ST19 to the map displayunit 110 as the data showing the recommended route. As a result, the mapdisplay unit displays the recommended route acquired through the routere-search on the monitor 2. After that, the navigation apparatusadvances the sequence to step ST22 and starts a route guidance.

In step ST22, the navigation apparatus starts a route guidance. Morespecifically, the route guidance unit 140 generates display data showinga guidance message on the basis of the route acquired through the searchin step ST15 or step ST19 and sends the display data to the monitor 2,and also generates audio data showing the guidance message and sends theaudio data to the audio speaker 4. Thereby, while the guidance messageis displayed on the monitor 2, the guidance message is outputted byvoice from the audio speaker 4. After that, guidance messagescorresponding to the environments which vary as the vehicle travels areoutputted in turn.

As previously explained, because the navigation apparatus in accordancewith Embodiment 1 of the present invention is constructed in such a wayas to, when a road where a car pool lane is also provided is included ina route acquired through a route search, present, as a recommendedroute, the route using the car pool lane if the distance over which thevehicle will travel this highway is equal to or longer than apredetermined value, the navigation apparatus does not present the carpool lane as the recommended route if the distance over which thevehicle will travel the road is shorter than the predetermined value.Therefore, when driving the vehicle to travel along the recommendedroute, the user does not need to cross general purpose lanes of ahighway and to make a useless lane change, and can therefore drivesafely while using car pool lanes properly.

Recently, there are cases in which gates intended only for a car poollane which is also provided on a highway are disposed. Therefore, in acase in which gates intended only for a car pool lane are used as aroute, the above-mentioned settings using the car pool lane conditionsetup screen are neglected.

INDUSTRIAL APPLICABILITY

As mentioned above, when a car pool lane is included in a route acquiredthrough a route search, the navigation apparatus in accordance with thepresent invention presents the route as a recommended route includingthe carpool lane if the traveled distance is equal to or longer than apredetermined value, so that the user does not need to cross generalpurpose lanes and to make a useless lane change during travel over ashort distance, and can therefore drive safely while using car poollanes properly. Therefore, the navigation apparatus in accordance withthe present invention is suitable for use in a vehicle-mountednavigation system and so on.

1. A navigation apparatus comprising: a map data acquiring means foracquiring map data including data about roads for which whether or not acar pool lane is also provided is specified; a current positiondetermining means for determining a current position; an input unit forinputting a destination; and a route searching unit for searching for aroute from the current position determined by said current positiondetermining means to the destination inputted by said input unit on abasis of the map data acquired by said map data acquiring means, andfor, when a road where a car pool lane is also provided is included inthe route which said route searching unit has acquired through saidsearch, presenting, as a recommended route, the route using said carpool lane when a distance over which said road will be traveled is equalto or longer than a predetermined value, while presenting, as therecommended route, the route using an general purpose lane of said roadwhen the distance over which said road will be traveled is shorter thanthe predetermined value.
 2. The navigation apparatus according to claim1, characterized in that said navigation apparatus includes a usable orunusable setting means for setting up information indicating use ornonuse of a car pool lane, as a route, according to a traveled distance,and the route searching unit searches for the route from the currentposition determined by said current position determining means to thedestination inputted by said input unit on a basis of the map dataacquired by said map data acquiring means, and, when a road where a carpool lane is also provided is included in the route which said routesearching unit has acquired through said search, presents, as therecommended route, the route using said car pool lane when said usableor unusable setting means sets up information indicating use of a carpool lane as a route and a distance over which said road will betraveled is equal to or longer than a predetermined value, whilepresents, as the recommended route, the route using an general purposelane of said road when the distance over which said road will betraveled is shorter than the predetermined value.
 3. The navigationapparatus according to claim 1, characterized in that said navigationapparatus includes a distance setting means for setting up a traveleddistance for a road for which a car pool lane is also provided, and theroute searching unit searches for the route from the current positiondetermined by said current position determining means to the destinationinputted by said input unit on a basis of the map data acquired by saidmap data acquiring means, and, when a road where a car pool lane is alsoprovided is included in the route which said route searching unit hasacquired through said search, presents, as the recommended route, theroute using said car pool lane when said usable or unusable settingmeans sets up information indicating use of a car pool lane as a routeand a distance over which said road will be traveled is equal to orlonger than the value set up by said distance setting means, whilepresents, as the recommended route, the route using an general purposelane of said road when the distance over which said road will betraveled is shorter than the value set up by said distance settingmeans.
 4. The navigation apparatus according to claim 2, characterizedin that the route searching unit neglects the settings set up by saidusable or unusable setting means when a gate which is intended only fora car pool lane and in which a vehicle directly enters the car pool laneis included in the route.